In the United States, the five-cent coin is currently prepared from a standard composition of 75% copper (Cu) and 25% nickel (Ni) by weight. The United States Mint has employed this composition since the inception of the five-cent piece in 1866. The standard composition provides properties that balance the needs of commerce while offering acceptable wear resistance with sufficient coinability to optimize die life during coin manufacturing. Additionally, and importantly, this composition also provides electromagnetic properties which are relied upon by the vending and banking industries.
While the combination of Cu and Ni have provided desirable properties for U.S. currency, both Cu and Ni have been subject to dramatic increases and fluctuations in cost during recent years, with the cost of raw metals exceeding the face value of the five-cent coin itself.
In 2012, the U.S. Mint reported that the total raw material cost for each five-cent coin was $0.06, with total production costs being $0.1009 per five cent coin. As a result, the financial implications have prompted legislation for an alternative to the current standard composition. At the same time, it is desired that critical-to-performance properties, such as wear resistance, coinability, corrosion resistance, and electromagnetic properties among others be maintained.
Stainless steels have been proposed as alternative materials for coining, since the base metal cost of iron is significantly less than Cu, and iron is readily available and less susceptible to price fluctuations. A popular example is type 430 stainless steel, currently being utilized as a coining and token alloy by some private and foreign mints.
However, 430 and other stainless alloys may lack characteristics desired by discriminating producers, including difficulty in striking, magnetic properties and so on. Foreign mints utilizing stainless alloys for coining attempt to circumvent premature die wear through design. In particular, these mints design images and lettering exhibiting shallow relief, or design, to facilitate striking of the coin and thus avoiding premature wear of the die. United States coinage tends to display deeper designs, which necessitate larger striking forces, leading to potentially decreases in die life.
Another problem with 430 and other stainless alloys is by nature they are ferromagnetic, which may considered be a detriment for coinage in the United States. For many foreign countries and the gaming industry magnetism is not considered an impairment for exclusion.
As a result, there is a desire for a new alloy for coining that utilizes significantly more cost effective raw materials and retains much of the desired properties of the known composition, such as wear resistance, strikability, corrosion resistance, and electromagnetic properties.